Venetian blinds and pleated blinds of modern design are frequently very thin and have a very slim, low profile headrail for accommodating the controlling cords of the blind. The cord locks which operate with these low profile headrails must match the profile of the headrail and not extend outside of the body of the blind or downwardly from the headrail. Such cord locks, nevertheless, must be capable of firmly locking the controlling cords of the blind in place without cutting or fraying of the cords, and they must be operable by pendulum manipulation of the cords from side-to-side. The cord locks must be interchangeable from left to right, and yet economy dictates that the cord locks have a minimum number of parts. It is, therefore, desirable that at least some of the movable parts be transferable from one side of the cord lock to the other when changing from left-hand to right-hand operation.
It is also desirable that the cord lock be capable of accommodating a colored cap which matches the coloring of the blind and headrail, and the cap must be firmly secured in place, so that it will not be dislodged even though it may be engaged and hit by the cords as they are being manipulated to raise or lower the blind. The cord lock constructed in accordance with the invention is adapted for either left-hand or right-hand operation with a simple reorientation of several parts of the mechanism and it may be quickly mounted in position on the headrail of the blind or shade.